Rob Scott wrote:
Ed
OK, I will bite...
We did that and found *one* instruction that was so slow, and executed so often, it
brought our product to its "knees".
Please name and shame the instruction
LMD. We used it in an unstack routine, that had been updated to support
AMODE(64) execution, without understanding just how slow it was (and how
often we executed it). Code got into the field for early testing and
customers complained. A product called STROBE pointed to the 64-byte
block containing this instruction. We replaced it with other
instructions and the problem was resolved.
Unfortunately, instruction timing is a moving target. In recent years,
some other instructions we use have become very slow. For example,
EX/NOPR has gone from 15 times as slow as LA on z9 to 95 times as slow
as LA on z10. (See my SHARE in Austin z10 User Experience for details.)
--
Edward E Jaffe
Phoenix Software International, Inc
5200 W Century Blvd, Suite 800
Los Angeles, CA 90045
310-338-0400 x318
edja...@phoenixsoftware.com
http://www.phoenixsoftware.com/
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